The use of cationic quaternary ammonium compounds (“quats”) for delivering fabric enhancing benefits in the laundry process is known. Examples of two classes of cationic quats for use in fabric softeners include: di-alkyl quats having two carbon chains of length 12 to 18 carbons in length, and mono-alkyl quats. See U.S. Pat. Nos. 6,291,421, 6,110,886, 5,919,751, 5,490,944, 4,888,119, 4,569,800; and US Publ. Nos. 2007/0105739, 2005/0020476.
It is believed that many fabric enhancer compositions comprising cationic quats having two alkyl or alkenyl chains tend to suffer from phase stability problems as demonstrated by the cationic quats aggregating over time ultimately resulting in the formation of flocs or other precipitates and even visible phase separation. This problem of phase stability is believed to be exacerbated when additional fabric enhancer actives, such as cationic polymers, are introduced into the composition. Compositional incompatibility is particularly problematic when the end product is made and packaged at a centralized manufacturing site, followed by being shipped great distances across varying temperatures and air pressures. Additionally, it is desired to minimize any compositional incompatibility problems in the end product over extended periods of time as the period between manufacturing and ultimate end use may be several months.
Manufacturers have introduced mono-alkyl quats as one way to avoid phase stability problems. Mono-alkyl quats, however, are rather expensive and may be inferior to di-alkyl quats, with respect to softening and antistatic benefits under certain laundering conditions. See U.S. Pat. No. 5,466,394, US Patent Publ. No. 2005/0164905, and WO 2006/072083. Other attempts to address compositional incompatibility include the addition of select solvent systems to control the behavior of the cationic quats. See e.g. U.S. Pat. Nos. 6,521,589, 6,211,140, 5,747,443, and US Publ. No. 2003/0060390. Many of these select solvent systems, however, are so expensive as to be cost prohibitive for commercial use. Additional attempts to improve phase stability include the use of processing technologies to create uni-lamellar vesicles of a specific size. See, e.g., US Publ. No. 2009/0042765A1. Additionally, attempts to formulate wash compositions comprising anionic and cationic surfactant complexes have been made for wash formulations. See, e.g. U.S. Pat. No. 5,204,010. These formulations however are designed as wash formulations typically comprising more anionic surfactant than cationic surfactant.
Despite these and other attempts to control compositional incompatibility, there remains an ongoing search for fabric enhancer compositions which are less susceptible to phase stability problems and are commercially viable from a cost perspective.